ME. E. J. MTERS ON GREENLAND CRUSTACEA. 65 



long. 19° 1' "W., with a few specimens of larval Cirripedia. On 

 account of its very small size, I doubt if this specimen can be 

 regarded as adult ; but should the characters given prove con- 

 stant, it may be designated after its discoverer, I. Whymperi. 



In the parallel sides of -the body and the existence of three per- 

 fectly distinct tail-segments besides the terminal segment, it has 

 much affinity with the Idotea parallela, S. Bate & Westwood, 

 ' Brit. Sessile-eyed Crust.' ii. p. 391 (1868) : but in that species 

 (not to speak of other differences) the terminal segment has the 

 sides parallel, and is semicircularly rounded at its distal ex- 

 tremity. 



The Idotea rugulosa of Buchholz, ' Zweite deutsche Nordpolarf. 

 Crust.' p. 285, 1874, note, from Spitzbergen, is also a species with 

 subparallel sides, but has the terminal segment emarginate at its 

 distal extremity. 



Idotea bicuspida, Owen, ' Cr. in Zool. of Capt. Beechey'sVoyage,' 

 p. 92, pi. xxvii. fig. 6 (1839), is at once distinguished by its more 

 oval form and the emarginate tip of the terminal tail-segment. 



Mqa crenulata. 



Mga. crenulata, Lutken, Naturhist. Foren. Vidensk. Meddelelser, p. 70, 

 pi. i. figs. 4, 5 (1858). 



A specimen of this fine species is in the collection, which was 

 purchased from a sailor at Umenak, who stated it to have been 

 parasitic on a Greenland Shark. A specimen also from Green- 

 land, in the British-Museum collection, presented some years ago 

 by Mr. Whymper, is said to have been parasitic either on the 

 Shark or the Cod. 



Its length is no less than 2 inches 5| lines (60 millims.). 



Mga psora, Linn. 



Oniscus psora, Linn. Syst. Nat. (ed. xii.) i. p. 1060 (1766) ; Pennant, 



Brit. Zool. iv. pi. xviii. fig. 1 (1777). 

 iEga emarginata, Leach, Linn. Trans, xi. p. 370 (1815); M.-Edw. 



Hist. Nat. Crust, iii. p. 240 (1840); Crust, in Cuv. R. A. (ed. 3), 



pi. Ixxvii. fig. 1. 

 jEga psora, Kroyer, Danmarks Fiske, 2nd deel, p. 40 (1843-45); 



Lutken, Naturhist. Foren. Vidensk. Meddelelser, p. 65 (1858); S. 



Bate $ Westwood, Brit. Sessile-eyed Crust, p. 238 (1862). 



Four specimens are in the collection, obtained with JE. crenu- 

 lata. The largest measures about 1 inch 7^ Hues. It is found in 

 the British, Scandinavian, Icelandic, and Greenland seas ; and 



